package com.wkbb.common.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author luowenyan
 * @version V1.0
 * @className NewMd5Util
 * @description 一个新的MD5加密工具类
 * @date 2019/9/6 11:53
 */
public class NewMD5Util {

    private static final Logger logger = LoggerFactory.getLogger(HttpClientUtil.class);
    /**
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符
     */
    protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6','7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    protected static MessageDigest messagedigest = null;
    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    public static String getFileMD5String(File file) throws IOException {
        InputStream fis;
        fis = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        int numRead = 0;
        while ((numRead = fis.read(buffer)) > 0) {
            messagedigest.update(buffer, 0, numRead);
        }
        fis.close();
        return bufferToHex(messagedigest.digest());
    }

    public static String getStringMD5(String str){
        byte[] buffer=str.getBytes();
        messagedigest.update(buffer);
        return bufferToHex(messagedigest.digest());
    }

    public static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换
        // 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同
        char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    public static String getMD5(String URLName){
        String name="";
        try {
            URL url = new URL(URLName);
            InputStream inputStream = new BufferedInputStream(url.openStream());
            byte[] bytes = new byte[1024];
            int len = 0;
            MessageDigest messagedigest = MessageDigest.getInstance("MD5");
            while ((len = inputStream.read(bytes)) > 0) {
                messagedigest.update(bytes, 0, len);
            }
            name = NewMD5Util.bufferToHex(messagedigest.digest());
            inputStream.close();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return name;
    }

    public static void main(String[] args){
        String fileUrl = "https://dynamic-test-1251785967.cos.ap-shanghai.myqcloud.com/wx323e0621aaa34047.o6zAJs2cHoxKpPhwR2DVArkN6RXU.8Gb4EFb9dwgk97db453bad2d8024869e5d50b2d0c57d.jpeg";
        System.out.println(NewMD5Util.getMD5(fileUrl));
        try{
            //getFileMD5String这个方法对远程文件无法进行加密,只能对本地文件加密?,以后有时间再研究
            System.out.println(NewMD5Util.getFileMD5String(new File("E:\\111.jpeg")));
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}
